Beautiful Georgian cruciform ring. 
Formed as a cross, the central stone a faceted amethyst in a gold button backed setting, with four high topped old cut diamonds for the four corners of the cross, also in decorative closed back settings.
The shoulders are typical of the period, with a silver foliate insert on the shoulder, with some understated decoration and a simple reeded shand to the rear.
 
A cruciform ring is a piece of jewelry with a "cross-shaped" design, featuring a central motif and often four surrounding points, resembling a cross. The term "cruciform" means "cross-shaped," and this design is evident in the arrangement of gems, often diamonds or other stones, in a central cluster or band. These rings frequently incorporate religious symbolism, with the cross representing faith.
 
size - just under a 7 and can be sized
face measures 13mm x 13.7mm
weighs - 2.9g
English circa 1770
Condition - excellent antique condition. Evidence of resizing